1. Field of the Invention
This invention relates to room temperature curable coating compositions, fabric binders, and adhesives.
2. Description of the Prior Art
Most high quality, highly crosslinked film-forming polymers to date have been cured with aminoplasts. However, due to problems with the use of formaldehyde, new coating, adhesive, and binder compositions have been needed which meet the performance specifications of such aminoplast compositions without the use of formaldehyde.
Low energy curing ("LEC") compositions which are formaldehyde-free have been previously suggested, but are, for the most part, relatively costly and do not perform adequately for many applications.
Oil soluble low temperature curing quaternary ammonium monomers have been described in a recent patent application of Thomas W. Hutton and Richard F. Merritt filed Aug. 7, 1981, Ser. No. 291,010, as have been homopolymers, copolymers of such monomers, and copolymers of such monomers with other ethylenically unsaturated monomers in the manner shown in U.S. Pat. No. 3,678,098 incorporated herein by reference. The patent also teaches activation of such polymers by raising the pH to make reactive and readily crosslinked coatings, binders, and adhesives.
Halohydroxypropyl dialkyl-ar-vinylphenylenylalkylenyl quaternary ammonium compounds, polymers thereof and uses of such polymers are taught by D. A. Winey in Patent Application Ser. No. 291,142 filed Aug. 7, 1981. The polymers are particularly useful as wet-strength agents in the making of paper.
Monoethylenically unsaturated quaternary ammonium monomers wherein the unsaturated group is an allyl or a double bond functionally equivalent to an isolated vinyl group, and thus readily polymerizable with vinyl acetate to provide emulsion polymers capable of low energy cure, are taught in the U.S. Patent Application of T. W. Hutton, Ser. No. 291,143 filed Aug. 7, 1981. The invention is also directed to addition polymers of such monomers and to methods of producing the monomers and the polymers. The polymers are useful, for example, as wet-strength agents in the making of paper.
A composition comprising a blend of (a) an emulsion acid copolymer and (b) an emulsion halohydroxypropyl ammonium copolymer, at least one of (a) or (b) being film forming at room temperature is taught in a U.S. Patent Application by M. L. Gioeni et. al. Ser. No. 320,283 filed Nov. 12, 1981. The invention also comprises activating the composition with base and applying the composition to a substrate to form a tough, solvent-resistant film on the substrate.
An object of the present invention is to provide low energy cured, high performance coatings, binders, and adhesives in formaldehyde-free systems having very high performance such as that of the aminoplast systems.
An additional object is to provide a unique process for activating and reacting such compositions which provides a long open time, and a stable formulation.
Another object is to provide films, coatings, binders, and adhesives which have excellent mechanical and chemical properties such as tensile strength and solvent resistance.
These objects, and others which will become apparent from the following disclosure, are achieved by the present invention which comprises in one aspect a composition comprising a blend of (a) an acid copolymer emulsion, and (b) a halohydroxypropyl ammonium salt copolymer solution. In other aspects, the invention comprises activating the composition with base and then applying to a substrate. In another aspect, the invention comprises the tough, solvent resistant films prepared by the process, and articles employing the films, coatings, binders or adhesives of this invention.
Employing a solution of the quaternary ammonium salt polymer permits the use of the relatively expensive quaternary ammonium salt component with high efficiency and effectiveness. This component polymer being in solution, can effectively enter any nooks and crannies created in the emulsion polymer particles during the drying of the blend. This effectiveness in crosslinking also has the effect of permitting the use of a lower carboxylic acid content in the emulsion polymer thus increasing the water and strong solvent resistance of that component and, thereby, of the product. Of particular utility, is the ability to use readily available quaternary ammonium salts, as crosslinking components in the solution polymer, to crosslink an emulsion polymer comprising monomers not readily copolymerizable with said readily available quaternary ammonium monomers.